Process of manufacturing an improved bituminous substance.



ED STATES PATENT OFFICE.

CLIFFORD RICHARDSON, OF NEW YORK, N. Y.

PROCESS OF MANUFACTURING AN IMPROVED BITUMINOUS SUBSTANCE.

No Drawing.

To all whom it may concern:

Be it known that I, CLIFFORD RICHARD- soN, residing at New York city, inthe county of New York and State of New York, have invented a certainnew and useful Process-of Manufacturing an Improved BituminousSubstance, whereof the following is a specification.

My invention relates to a process whereby I impart to bituminoussubstances a higher degree of body or stability.

It has heretofore been well known that the addition of finely dividedmineral matter to bituminous substances increases their body and thishas been availed of in the paving and other arts. Thus, in the making ofa bituminous paving mixture, it has been customary to add to thebitumen, in addition to the coarser mineral aggregate, a certainproportion of impalpable powder and the utility of this addition hasbeen recognized.

According to my invention, I obtain in liquid or semi-liquid orsemisolid bituminous substances an increased or greater degree of bodyand stability over and above that of the material as ordinarily prepared(meaning thereby a greater resistance to deformation under pressure), bymeans of the addition, in the manner hereafter specified of solid matterin a highly dispersed colloidal state. I attribute this result in partat least, to the enormous surface area which matter in a highlydispersed colloidal state presents per volume of weight, andconsequently the enormous amount of surface energy developed.

In this specification when I use the phrase bituminous substance, I wishit to be understood that I am including not only those substances whichare now classified as bitumen whether native or artificial, but alsosubstances which exhibit similar characteristics. For example, I amreferring not only to the residual pitches which are the products of thedistillation of petroleum, but I am also referring to the coal tarpitches and like plastic organic substances.

I will illustrate my invention with reference to its application to theimprovement of residual pitches, such as are commonly used in the pavingarts, (but this will be understood as being an illustration, rather thana restriction of my invention), and more particularly with relation toits application to the paving arts.

Substances which form apparently homogeneous solutions in liquids andwhich are not removed therefrom by ordinary filters, but which will notdifl'use through a membrane, and observation of which under theultra-microscope shows to be dispersed in solid form, are known asdisperse colloids, or the disperse phase of matter in a colloidal state;the other component of the system lscommonly spoken of as the continuousphase.

According to my process I incorporate with a bltuminous substance aproper proportion of a substance in the state of a disperse colloid, asfor example, a fine clay. The intimate and uniform dispersion of clay ina colloidal state throughout the bitumlnous substances cannot be verywell accomplished by merely adding the clay to the bitumen, but I havediscovered that by first comblning the clay with a proper amount ofwater in the form of an aqueous paste and then adding this paste to thebituminous substance, .agitating the combination and subsequentlyevaporating the water, I accomplish the required intimate dispersion ofthe clay in its colloidal state throughout the bituminous substance, tosecure the bencfits of my invention. Accordingly the clay which is to bedispersed in relation to the Specification of Letters Patent. Patentedsept lg, 1916 Application filed August 24, 1914. Serial No. 858,335.

bitumen, must be of a sufiicient degree of fineness to be capable ofexisting in a colloidal condition in relation to Water, as well as inrelation to bitumen.

In practice I prepare an aqueous paste by the addition of water to aclay capable of furnishing the desired amount of such a dispersecolloid. WVith highly colloidal clays, I have used three parts of waterto one of clay. WVith poorer clays more water may be employed. Thispaste is added to a bituminous substance in proportions varymg with thecharacter of the substance and the object for which the material is tobe used. The amount of disperse colloid should be at least one or twoper cent, but may be increased to any percentage at which the bitumenwill melt and flow. But it will be understood that if the proportion ofclay is too large, the bitumen is incapable of constituting a continuousphase in relation to the clay, and accordingly instead of matter in acolloidal state, there results a mere mixture which does not constitutemy invention. Proper agitation of the paste and the bitumen with steamor air will effect unihas been associated is then removed as byevaporation.

As an example of the advantageous practice of my invention in connectionwith the paving industry, I may add to any crude petroleum, maltha orliquid residuum from the distillation thereof, or to any form of bitumensufficiently liquid below the temperature of boiling water, to make anemulsion with the clay paste, from twenty.to fifty per cent. of a liquidpaste consisting of water and clay containing disperse colloidal matter,varying in amount according to the quality of the clay, but, of course,the more desirable the larger percentage of this material although thecoarser portion may be looked upon as desirableas an ordinary filler,although undesirable if it is sufficiently coarse to settle out duringdistillation and thus form a cake or coke upon the walls of the still.emulsified by passing through it steam or air or by other means ofagitation, and evaporating the water, incidentally in some casesdistilling ofl some or all of the more Volatile portions of the bitumen,according to the uses to which the resulting residual pitch is to be putin the preparation of asphaltic cements for paving mixtures.

By accomplishing the addition of the disperse colloid to the bituminoussubstance, in the form of aqueous paste, I am able to secure itsdispersion throughout and intimate association with the bituminoussubstance in a thoroughly uniform manner with the production of asubstance in a truly colloidal form, of which the bitumen Thiscombination isconstitutes the continuous phase. result or product hasbeen secured Where attempts have heretofore been made to add finelydivided mineral matter directly to a bituminous substance in the attemptto thereby secure increased stability of the product. Nor have suchresults been attained where attempts have been made to add tar to clay,in such proportions that the mixed ingredients are incapable of assumingcolloidal relations to each other. I believe my improved result to bedue to the uniform dispersion secured by adding to the bitumen thefinely divided matter in the state of a disperse colloidalreadyintimately combined with Water. This accomplishes similar dispersion ofthe substance throughout the bitumen, notwithstanding the subsequentremoval of the water.

Having thus described my invention, I claim:

The process of increasing the stability of bituminous substances, whichconsists in preparing an aqueous paste of clay of such fineness as to becapable of colloidal dispersion with relation to the water, combiningsuch paste lntimately and uniformly with a sufiicient quantity of thebituminous substance for the latter to form a continuous phase andaccomplish the colloidal dispersion of the clay with relation to thebitumen, and removing the water.

In testimony whereof, I have hereunto signed my name at Philadelphia,Pennsylvania, this eighteenth day of August, 1914.

CLIFFORD RICHARDSON. Witnesses:

JAMES H. BELL, E. L. F ULLERTON.

No such

